[dns-operations] [DNSOP] DNSSEC threshold signatures idea

[Hugo Salgado-Hernández]

Hi Mukund.
I talked about this to Davey in Montreal. There's an implementation
in github[1] and presentations in OARC[2] and ICANN[3].

I'm not sure if its being used right now in a live zone, but certainly
in labs and testing. There's been some interests with academic
institutions, but don't think they're ready yet.

We've been trying to focus this technology as a "poor-man" HSM, as
having similar security features without buying an expensive HW.
But I think the root and similar high-value zones will benefit for
having an split of the private key AND the fact of not needing a
"root key ceremony" to sign, because you can sign remotely with
each piece of the private key, and transmit the "signature pieces"
to a central place.

Hugo

[1] https://github.com/niclabs/docker/tree/master/tchsm
[2] <https://indico.dns-oarc.net/getFile.py/access?contribId=22&sessionId=3&resId=1&materialId=slides&confId=20>
[3] <http://buenosaires48.icann.org/en/schedule/wed-dnssec/presentation-dnssec-cryptographic-20nov13-en>
 
  
On 21:42 06/09, Mukund Sivaraman wrote:
> During a coversation about the Yeti project, Davey Song brought up an
> idea about using threshold signatures within DNSSEC. While he talked
> about it primarily for the root zone within the context of having
> multiple signers for it, I'm curious to know what operators think about
> the concept for other zones, and if there's any interest in having a
> working implementation.
> 
> DNSKEY RRs contain public keys. Corresponding secret keys are managed by
> signing entities in various ways:
> 
> * It may be for a low-risk zone and a human may leave the key on the
>   nameserver itself
> 
> * The key may be held by some number of trustworthy staff offline and
>   when signing is required, one of them signs the zone and returns the
>   signed zone
> 
> * It may be managed by an automated system under the control of one or
>   more people
> 
> * It may be held in a locked computer system which may be accessed when
>   multiple trustworthy "keepers" are present
> 
> * There may be schemes like this:
>   https://www.icann.org/news/blog/the-problem-with-the-seven-keys
> 
> In many of these cases, it may be possible for one rogue person to sign
> records against the wish of the rest of the trustworthy group appointed
> by a zone owner. Even though it's unlikely, it's possible to do so
> because the control over secret key material may be available to one
> person, even if it is wrapped in multiple layers.
> 
> The concept of threshold crypto is that there is a public DNSKEY, for
> which the secret key is not available in a single form where it can be
> reconstructed. Instead, N members of a group have some key material each
> respectively, and any M (< N) members of the group may work together to
> prepare RRSIGs by using their respective key materials individually, and
> collaborating to generate the signatures.
> 
> It may be possible for such a scheme to be compatible with existing
> DNSSEC algorithms. Is there any operator interest in this?
> 
> 		Mukund
> 
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